13 - Lymphatic System

Question 1

What are the three types of extracellular fluids?

Answer 1

1)	blood plasma
	fluid in blood
2)	ISF (interstitial fluid) 
	bathes cells (except blood cells)
3)	Lymph 
	inside lymphatic vessels

Question 2

Describe lymphatic circulation.

Answer 2

 ISF (Interstitial Fluid) – formed by capillaries leaking plasma
o 90% re-enters blood in capillaries + venules
o 10% into lymphatic circulation (now called lymph)
 Lymph
o enters lymphatic capillaries (closed ended vessels)
o lymphatic capillaries connect to lymphatic collecting vessels (have valves)
 lymph nodes along vessels filter lymph (bacteria, debris)
 transport lymph fluid AWAY from tissues to:
1) Right lymphatic duct (lymph from Right head, chest, + arm)
 drains into right subclavian vein reentering circulation
2) Thoracic duct (lymph from below ribs + Left body)
 collecting vessels from below the ribs converge to an enlarged lymph vessel = cisterna chyli (the beginning of the thoracic duct)
 thoracic duct drains into L. subclavian vein reentering blood circ.

Question 3

What are the lymphatic tissues and organs?

Answer 3

1) Primary lymphatic organs + tissues:
a) red bone marrow
 lymphocytes arise here
 B lymphocytes mature and proliferate (mitosis) here
b) thymus gland
 T lymphocytes mature and proliferate (mitosis) here
2) Secondary lymphatic organs + tissues: (where lymphocytes proliferate)
a) lymph nodes
 locations:
o cervical, axillary (armpit), inguinal (groin), intestinal, pelvic
b) spleen
 filters blood
o e.g. removes bacteria
c) Mucosal Associated Lymphoid Tissue (MALT)
 e.g. tonsils, appendix, lymphoid tissues on mucous membranes
 tonsils:
i. adenoids = pharyngeal (1) – nasopharynx
ii. palatine (2) – in oropharynx – commonly removed
iii. lingual (1) – base of posterior part of tongue